Upright vacuum cleaner with cyclonic air flow

ABSTRACT

An upright vacuum cleaner includes an upright housing section and a nozzle section. A cyclonic airflow dirt and dust separating chamber is defined in said upright housing section. A suction source pulls air and entrained dirt, dust, and other contaminants through a main suction opening formed in the underside of the nozzle and into the cyclonic airflow chamber. The cyclonic airflow chamber causes the suction airstream to travel in a cyclonic path such that the entrained contaminants are separated therefrom and deposited into a dirt container that defines the chamber. A main filter element filters residual contaminants from the suction airstream between the chamber and the suction source. The main filter element is preferably made from high-density polyethylene porous filter media. A final filter assembly filters the suction airstream discharged by the suction source to ensure that the air discharged into the atmosphere is contaminant free, including those contaminants introduced into the airstream by the suction source itself.

[0001] This application is a continuation-in-part of application Ser.No. 09/122,541 filed on Jul. 24, 1998 and still pending. Thatapplication is, in turn, a continuation-in-part of application Ser. No.09/004,999 filed Jan. 9, 1998 and still pending.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to vacuum cleaners. Moreparticularly, the present invention relates to upright vacuum cleanersused for suctioning dirt and debris from carpets and floors.

[0003] Upright vacuum cleaners are well known in the art. The two majortypes of these vacuum cleaners are a soft bag vacuum cleaner and a hardshell vacuum cleaner. In the hard shell vacuum cleaner, a vacuum sourcegenerates the suction required to pull dirt from the carpet or floorbeing vacuumed through a suction opening and into a filter bag housedwithin the hard shell upper portion of the vacuum cleaner.

[0004] To avoid the need for vacuum filter bags, and the associatedexpense and inconvenience of replacing the bag, another type of uprightvacuum cleaner utilizes cyclonic air flow, rather than a filter bag, toseparate the majority of the dirt and other particulates from thesuction air stream. The air is then filtered to remove residualparticulates, returned to the motor and exhausted.

[0005] For many of the prior art cyclonic air flow vacuum cleaners, theprocess of emptying the dirt collection container has been foundinconvenient and often resulted in the spillage of the cup contents.Also, the replacement of filter elements in these units has not beenconvenient.

[0006] In some cyclonic air flow vacuum cleaners, the exhaust air is notfree of residual contaminants. Because the cyclonic action of suchconventional cyclonic vacuum cleaners does not completely remove alldust, dirt and other contaminants from the suction air stream, it isnecessary to include a filter downstream from the cyclonic chamber.However, the conventional filter elements so used have causedconsiderable difficulty. A conventional filter which is sufficientlyfine to filter the air stream effectively, unduly restricts air flow anddecreases the effectiveness of the cyclonic action. On the other hand, acoarse filter does not effectively filter the air stream of residualcontaminants. Furthermore, conventional filter media, such as paper orfibrous media, has been found to clog readily thereby unduly decreasingair flow rates over time.

[0007] Accordingly, it has been deemed desirable to develop a new andimproved upright vacuum cleaner having a cyclonic air flow which wouldovercome the foregoing difficulties and others while providing betterand more advantageous overall results.

SUMMARY OF THE INVENTION

[0008] According to the present invention, a new and improved uprightvacuum cleaner is provided.

[0009] In accordance with the first aspect of this invention, a vacuumcleaner includes a housing defining a cyclonic air flow chamber forseparating contaminants from a suction air stream. The housing includesan inlet for the chamber and an outlet for the chamber. The suction airstream inlet and outlet are both in fluid communication with thecyclonic air flow chamber. A suction opening is defined on the housing.The suction opening is fluidically connected with the cyclonic air flowchamber inlet. An air stream suction source is located on the housing.The suction source has an inlet fluidically connected to the cyclonicchamber outlet and a suction source outlet. The suction sourceselectively establishes and maintains a suction air stream from thesuction opening to the suction source outlet. A main filter supportextends upwardly from the floor of the housing for releasably securing amain filter element centrally in the cyclonic air flow chamber. A mainfilter element is secured thereto. A dirt cup is selectively positionedin the housing with the main filter element being located in the dirtcup.

[0010] One advantage of the present invention is the provision of a newand improved vacuum cleaner.

[0011] Another advantage of the invention is found in the provision ofthe vacuum cleaner with a cyclonic air flow chamber through which thesuction air stream flows for separating dust and dirt from the airstream and for depositing the separated dust and dirt into an easily andconveniently emptied dirt cup.

[0012] Still another advantage of the present invention resides in theprovision of a cyclonic air flow upright vacuum cleaner with a mainfilter that effectively filters residual contaminants from the suctionair stream between the cyclonic air flow chamber and the motor assemblywithout unduly restricting air flow and without premature clogging.

[0013] Yet another advantage of the present invention is the provisionof a cyclonic air flow upright vacuum cleaner in which a direct air pathis provided between a suction air flow inlet, a suction air flow outletand a vacuum source preferably positioned directly beneath the suctionair flow outlet.

[0014] Still yet another advantage of the present invention is theprovision of a cyclonic air flow upright vacuum cleaner with a finalfilter located downstream from the suction motor assembly for filteringthe suction air stream immediately prior to its exhaustion into theatmosphere.

[0015] A further advantage of the present invention is the provision ofa vacuum cleaner with a tangential dirty air inlet into a dustseparation chamber and an axial clean air outlet from the dustseparation chamber, wherein the outlet is separated from the inlet by afilter. Preferably, the dirty air inlet is located at an upper end ofthe dust separation chamber and the outlet is located at a lower endthereof.

[0016] A yet further advantage of the present invention is the provisionof a vacuum cleaner with a cyclonic air flow chamber whereinaccummulated dust and dirt in the chamber serve as a filter means forfurther filtering at least a portion of the suction air stream passingthrough the chamber.

[0017] A yet further advantage of the present invention is the provisionof a vacuum cleaner with a cyclonic air flow chamber and a main filterelement wherein the main filter element is positioned in a removabledirt cup at least partially defining the cyclonic air flow chamber forease of emptying the dirt cup and for cleaning the filter.

[0018] Still other benefits and advantages of the invention will becomeapparent to those of average skill in the art upon a reading andunderstanding of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention may take form in certain components and structures,preferred embodiments of which will be illustrated in the accompanyingdrawings wherein:

[0020]FIG. 1 is a perspective view illustrating a cyclonic air flowupright vacuum cleaner in accordance with a first embodiment of thepresent invention;

[0021]FIG. 2 is a front elevational view of the vacuum cleanerillustrated in FIG. 1;

[0022]FIG. 3 is a right side elevational view of the vacuum cleaner ofFIG. 1;

[0023]FIG. 4 is an enlarged right side elevational view in cross sectionof the vacuum cleaner of FIG. 1 showing air flow through the cyclonicair flow dust and dirt separating chamber;

[0024]FIG. 5 is an exploded perspective view of a dust cup cylinder,filter rack and filter employed in the vacuum cleaner of FIG. 4;

[0025]FIG. 6 is a schematic view of a cyclonic air flow dust and dirtseparating chamber and adjacent components of a vacuum cleaner accordingto a second preferred embodiment of the present invention;

[0026]FIG. 7 is an exploded schematic perspective view of a dust cupcylinder, filter rack and filter employed in the vacuum cleaner of FIG.6;

[0027]FIG. 8 is an assembled schematic perspective view of the dust cup,filter rack and filter of FIG. 7 with a lid spaced away therefrom; and,

[0028]FIG. 9 is a greatly enlarged side elevational schematic view of amotor and seal interface for the vacuum cleaner of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Referring now to the FIGURES, wherein the showings are forpurposes of illustrating preferred embodiments of the invention only andnot for purposes of limiting the same, FIGS. 1-5 illustrate an uprightvacuum cleaner A including an upright housing section B and a nozzlebase section C. The sections B,C are pivotally or hingedly connectedthrough the use of trunnions or another suitable hinge assembly D sothat the upright housing section B pivots between a generally verticalstorage position (as shown) and an inclined use position. Both theupright and nozzle sections B,C are preferably made from conventionalmaterials such as molded plastics and the like. The upright section Bincludes a handle 20 extending upward therefrom by which an operator ofthe vacuum A is able to grasp and maneuver the vacuum.

[0030] During vacuuming operations, the nozzle base C travels across thefloor, carpet, or other subjacent surface being cleaned. With referencenow to FIG. 4, an underside 24 of the nozzle base includes a mainsuction opening 26 formed therein which extends substantially across thewidth of the nozzle at the front end thereof. As is known, the mainsuction opening 26 is in fluid communication with the vacuum uprightbody section B through a passage and a connector hose assembly 34 (FIG.3). A rotating brush assembly 36 is positioned in the region of thenozzle main suction opening 26 for contacting and scrubbing the surfacebeing vacuumed to loosen embedded dirt and dust. A plurality of wheels38 support the nozzle on the surface being cleaned and facilitate itsmovement thereacross.

[0031] The upright vacuum cleaner A includes a vacuum or suction sourcefor generating the required suction airflow for cleaning operations. Asuitable suction source, such as an electric motor and fan assembly E,generates a suction force in a suction inlet and an exhaust force in anexhaust outlet. The motor assembly airflow exhaust outlet is in fluidcommunication with a final filter assembly F (FIG. 2) for filtering theexhaust airstream of any contaminants which may have been picked up inthe motor assembly immediately prior to its discharge into theatmosphere. The motor assembly suction inlet, on the other hand, is influid communication with a cyclonic suction airflow dust and dirtseparating region G of the vacuum A to generate a suction force therein.

[0032] The cyclonic suction air flow dust and dirt separating region Ghoused in the upright section B includes a cyclonic airflow chamber 54defined by an upper fixed housing member 50 a and a lower dirt cup orcontainer 52 which is pivotally and releasably connected to the upperhousing B of the vacuum cleaner.

[0033] The suction airstream enters an upper portion of the cylconicdust and dirt separation chamber 54 through a generally tangentialsuction airstream inlet which is formed in the upper section 50 a of themain filter housing assembly 50. The suction airstream inlet of thechamber 54 is in fluid communication with a suction airstream hose 82through a fitting 84 as illustrated in FIG. 2.

[0034] With reference now to FIG. 1, the dirt container 52 is connectedto the vacuum cleaner upright section B through the use of a hingeassembly 90 which allows the dirt container to pivot between anoperative upright position and an open forwardly tilted position. Ahandle 96 is provided on an exterior of the container 52 to facilitateoperator movement of the container between the operative, open, andremoved positions. A latch 98 (FIG. 2) retains the dirt container in theoperative position. The latch 98 is biased through the use of a springor other resilient member or via the natural resiliency of the plasticfrom which it is molded. The dirt container has an upper edge 100defining an upper open end of the container. This end is preferablyinclined downwardly in a direction away from the handle 20. This edgemates with the adjoining edge 102 of the upper housing member.

[0035] The dirt cup 52 includes a main filter support, such as a post,stem or like structure 150 extending upwardly from a floor or base 152thereof. The post 150 is positioned in a central region of a cyclonicairflow chamber 154. A hollow cylindrical main filter element K ispositioned over the main filter support 150.

[0036] With reference now to FIG. 5, the filter element K is engaged inan interference fit with vanes 154 and a disk-like plateau 156 locatedon the floor 152 of the filter support so that the filter is releasablyyet securely retained in its operative position, even when the dirt cup52 is removed from the vacuum cleaner and inverted for purposes ofemptying the contents thereof. A filter locking means 158 accommodatinga gasket 159 is provided along the uppermost edge of the main filterelement K. The main filter element K extends upwardly from the dirt cupfloor 152 to a level approximately equal to an upper edge 100 of thedirt cup. Most preferably, as shown herein, the upper edge of the mainfilter element K is also sloped in the same manner as is the dirt cupupper edge 100. Over the entire height of the dirt cup 52, an annularcyclonic airflow passage is defined between the main filter K and thedirt cup 52. The base 152 serves also as the base of the dirt cup 52. Tothis end, the base 152 is suitably secured by conventional means to theside walls forming the dirt cup.

[0037] The filter element K preferably comprises POREX brand, highdensity polyethylene-based, open-celled, porous media availablecommercially from Porex Technologies Corp. of Fairburn, Ga. 30212, or anequivalent foraminous filter media. This preferred filter media is arigid open-celled foam that is moldable, machinable, and otherwiseworkable into any shape as deemed advantageous for a particularapplication. The preferred filter media has an average pore size in therange of 45 μm to 90 μm. It can have a substantially cylindricalconfiguration as is illustrated in FIG. 5, or any other suitable desiredconfiguration. The filter element could also have a convoluted outersurface to provide a larger filtering area. Some filtration is alsoperformed by the dirt in the bottom end of the dirt cup in the dirt L asshown by the arrow M.

[0038] With reference now to FIG. 6, a cyclonic suction airflow dust anddirt separating region M according to a second preferred embodiment ofthe present invention is there illustrated. This embodiment includes adust and dirt cup or container 202. The container has a substantiallyclosed lower end 204 having a centrally positioned aperture 205 thereinand an open upper end 206. A lid 208 (FIG. 8) can be selectively placedon the container or dirt cup.

[0039] Disposed within the dirt cup 202 is a filter and rack assembly210. Defined between an inner wall of the dirt cup 202 and the filterand rack assembly 210 is a cyclonic chamber 212 which communicates witha suction inlet passage 214 extending into an upper end of the cyclonicairflow chamber 212. The inlet opening is oriented tangential to thecyclonic chamber 212 so as to encourage a cyclonic airflow.

[0040] With reference now to FIG. 7, the filter and rack assemblyincludes a filter rack 220 having three vanes 222 which radiate awayfrom each other like the spokes on a wheel. In other words, the vaneassembly is Y-shaped in cross section. The filter rack is mounted on abase 224. Located at the bottom end of the base are three openings 226which are separated from each other by the vanes 222 and extend only asfar radially outwardly from a center point of the base 224 as is thelength of each vane 222. A filter element 230 is supported on the filterrack. The filter element is a hollow member having an open lower end 232which allows access to a hollow interior 234 of the filter. However, thefilter can have a closed top end 236.

[0041] The interior 234 of the filter 230 is so sized as to allow thefilter to be slipped over the vanes 222. The open lower end 232 of thefilter thus is seated on the plate 224. However, the hollow interior 234of the filter is in communication with the several openings 226extending through the filter rack base 224. The filter rack base ispreferably secured by conventional means to the open lower end 204 ofthe dirt cup cylinder 202 to close same. The upper end 206 of the dirtcup remains open.

[0042] With reference now also to FIG. 9, positioned beneath a bottomface 240 of the dirt cup 202 is an elastomer ring seal 242 which has acentral aperture 244 extending therethrough. The seal 242 is seatedaround the openings 226 of the filter rack base 224. A dirt cup supportwall 245 of a housing of the vacuum cleaner contains a central opening246 which is aligned with the aperture 244. An enlarged diameter section248 is disposed on an upper face of the wall 245. Adapted to be housedin the opening is a post filter element 249. The post filter 249 can bemade from a suitable conventional open cell foam plastic material, if sodesired. The support wall 245 is meant to sit on a motor support wall250 for mounting a suction motor N. The motor support has a centrallylocated bore 252 extending therethrough. The bore also includes anenlarged diameter section 254 defined on its lower face. A motor seal256 has a reduced diameter upper end 258 which is accommodated in theenlarged diameter lower end 254 of the motor support 250. A centrallylocated bore 260 extends through the motor seal. In this embodiment, themotor and fan assembly N is positioned directly beneath the motor seal256.

[0043] As is evident from FIG. 6, an in-line flow path is thus providedfrom the dust inlet 214 through the motor and fan assembly N. Morespecifically, dirty air flows into the dust inlet 214 and thus into thecyclonic chamber 212 defined within the dirt cup 202. As illustrated bythe arrow 260 the airflow into the chamber 212 is tangential. Thiscauses a vortex-type flow as is illustrated by arrows 262. Such vortexflow is directed downwardly in the dust chamber 212 since the top endthereof is blocked by the lid 208. The air flows radially inwardly andthrough the filter 230. The air then flows axially downwardly throughthe hollow interior of the filter 230 as illustrated by arrow 264.Subsequently, the air flows through the support wall opening 246, themotor support opening 252 and into and through the suction motor and fanassembly N as is illustrated by arrow 266. After being exhausted fromthe motor and fan assembly, the air flows through a conduit 270 definedin the upright housing section of the vacuum cleaner and into a plenum272 which holds an output filter 274. This is illustrated schematicallyby the arrows 276 and 278 in FIG. 6.

[0044] Suction airflow from the cyclonic chamber 212 is not able tobypass the main filter element 230, but instead must pass therethroughand be filtered of residual contaminants due to the existence of theseal 242. However, should there be some reason why there is a leakbetween the filter 230 and the filter rack base 224, the post filter 249(FIG. 9) will prevent dirt from being sucked directly into the motor andfan assembly N.

[0045] The conduit 270 is itself in fluid communication with theelongated plenum 272 that opens to the atmosphere and houses filtermedia 274. A protective grid or grate structure is snap-fit or otherwiseeffectively secured over the plenum 272 to secure the filter media inplace. The filter media is preferably a high efficiency particulatearrest (HEPA) filter element in a sheet or block form. Those skilled inthe art will recognize that even if the motor/fan assembly N causescontaminants to be introduced into the suction airstream downstream fromthe main filter element, the final filter assembly P will remove thesame such that only contaminant-free air is discharged into theatmosphere.

[0046] The location of the inlet 214, the outlet 216, and the generallycylindrical configuration of the cyclonic airflow chamber 212 causes thesuction airstream to follow a swirling or cyclonic path downward withinthe chamber 212 and then radially inward through the filter 230 to movedownwardly through the inside of the centrally located main filter 230.The orientation of the inlet 214 will affect the direction of cyclonicairflow, and the invention is not meant to be limited to a particulardirection, i.e, clockwise or counterclockwise.

[0047] Those skilled in the art will certainly recognize that the term“cyclonic” as used herein is not meant to be limited to a particulardirection of airflow rotation. This cyclonic action separates asubstantial portion of the entrained dust and dirt from the suctionairstream and causes the dust and dirt to be deposited in the dirt cupor container 202. The suction airstream then passes through the mainfilter element 230 so that residual contaminants are removed, and exitsthe cyclonic chamber 212 through the aperture 244 in the seal 242 andthrough the aperture 246 formed in the dirt cup support wall 245. Thesuction airstream is communicated to the motor/fan assembly N andexhausted through conduit 270 to the final filter assembly P where it isfiltered again by the HEPA filter 274 to remove any contaminants thatmay have passed through the filter 230, and any contaminants in theairstream due to its passage through the motor/fan assembly N.

[0048] The main filter element 230 can be cleaned by washing it, eithermanually or in a dishwasher—since it is dishwasher-safe—to remove dustor dirt particles adhering to the filter element. It is, however,important that the filter 230 be dried before it is used again. Thefinal filter media of the filter assembly 274, however, can not becleaned and must be replaced when it becomes clogged.

[0049] The invention has been described with reference to the preferredembodiments. Obviously, modifications and alterations will occur toothers upon reading and understanding the preceding detaileddescription. It is intended that the invention be construed as includingall such modifications and alterations insofar as they come within thescope of the appended claims or the equivalents thereof.

Having thus described the preferred embodiments, the invention is nowclaimed to be:
 1. A vacuum cleaner comprising: a housing defining acyclonic airflow chamber for separating contaminants from a suctionairstream, said housing further comprising an inlet for said cyclonicairflow chamber and an outlet for said cyclonic airflow chamber; anozzle base including a main suction opening, said main suction openingbeing fluidically connected with said cyclonic airflow chamber inlet; anairstream suction source having an inlet disposed adjacent said cyclonicairflow chamber outlet and a suction source exhaust outlet spaced fromsaid cyclonic airflow chamber, said suction source selectivelyestablishing and maintaining an approximately linear suction airstreamfrom said said outlet of said cyclonic airflow chamber to said inlet ofsaid airstream suction source; and, a main filter assembly positionedbetween said cyclonic airflow chamber and said suction source forfiltering contaminants from said suction airstream.
 2. The vacuumcleaner as set forth in claim 1 wherein said main filter assemblycomprises a filter element including a high-density polyethylene porousfilter media which includes pores having an average pore size ofapproximately 45 μm to approximately 90 μm.
 3. The vacuum cleaner as setforth in claim 1 wherein said filter element is approximatelycylindrical in shape.
 4. The vacuum cleaner as set forth in claim 3wherein said filter element has a convoluted outer surface.
 5. Thevacuum cleaner as set forth in claim 1 wherein said cyclonic airflowchamber inlet is disposed tangentially adjacent an outer periphery ofsaid cyclonic airflow chamber and said cyclonic airflow chamber outletis parallel to a longitudinal axis of said cyclonic airflow chamber. 6.The vacuum cleaner as set forth in claim 1 further comprising a finalfilter assembly positioned on one of said housing and said nozzle base,said final filter assembly being in fluid communication with saidsuction source exhaust outlet for filtering said suction airstreamexhausted from said suction source into the atmosphere.
 7. The vacuumcleaner as set forth in claim 6 wherein said final filter assemblycomprises a high efficiency particulate arrest (HEPA) filter media. 8.The vacuum cleaner as set forth in claim 1 wherein a lower portion ofsaid cyclonic airflow chamber is defined by a dirt container forreceiving and retaining dirt and dust separated from said suctionairstream, said container being pivotable between an operative positionand an open position, and including an open upper end defined by aninclined edge such that when said dirt container is pivoted fully intothe open position, the inclined edge is located in a substantiallyhorizontal plane to inhibit spillage of the separated dirt and dust. 9.An upright vacuum cleaner comprising: an upright housing sectionincluding a handle; a nozzle base section hingedly interconnected withthe upright housing section, said nozzle base section including a mainsuction opening formed in an underside thereof; a cyclonic airflowchamber defined in said upright housing section for separating dust anddirt from a suction airstream, said cyclonic airflow chamber includingan air inlet and air outlet; a suction source located in one of saidupright housing section and said nozzle base section and having asuction airflow inlet in fluid communication with said cyclonic chamberoutlet and a suction airflow outlet; a main filter assembly locatedbetween said cyclonic airflow chamber and said suction source forfiltering residual dust and dirt from a suction airstream as it flowsthrough said cyclonic airflow dust and dirt separating chamber; and,wherein an inlet of said suction source is co-linear with said cyclonicchamber outlet.
 10. The upright vacuum cleaner as set forth in claim 9further comprising a final filter assembly located on one of saidhousing and said nozzle base, said final filter assembly being in fluidcommunication with said suction airflow outlet of said suction sourcefor filtering said suction airstream exhausted by said suction sourceprior to said suction airstream being dispersed into the atmosphere andwherein said final filter assembly comprises a high efficiencyparticulate arrest (HEPA) filter media.
 11. The upright vacuum cleaneras set forth in claim 9 wherein said main filter assembly comprises afilter element including porous high-density polyethylene foam filtermedia.
 12. The upright vacuum cleaner as set forth in claim 11 whereinsaid porous filter media has pores with an average pore size of lessthan approximately 90 μm.
 13. The upright vacuum cleaner as set forth inclaim 9 further comprising an interference plate on which a main filterof said main filter assembly is mounted.
 14. The upright vacuum cleaneras set forth in claim 9 further comprising a dirt cup, wherein saidcyclonic airflow chamber is defined within said dirt cup and between aninterior wall thereof and an exterior wall of said main filter assembly.15. A vacuum cleaner comprising: a nozzle section; a housing sectionconnected to said nozzle section and in fluid communication with saidnozzle section; a dirt cup selectively mounted in said housing section;a cyclonic airflow chamber located in said dirt cup for separating dirtand dust from a suction airstream flowing into said housing sectionbetween an inlet located adjacent a first end of said housing sectionand an outlet located adjacent a second end of said housing section; afilter assembly located in said dirt cup, said filter assemblycomprising: a filter rack, and a first filter element mounted on saidfilter rack.
 16. The upright vacuum cleaner as set forth in claim 15further comprising a suction source having an inlet located directlybeneath said outlet of said dirt cup.
 17. The upright vacuum cleaner asset forth in claim 15 wherein said cyclonic airflow chamber inlet islocated on a periphery of said dirt cup and said cyclonic airflowchamber outlet is located along a longitudinal axis of said dirt cup.18. The upright vacuum cleaner as set forth in claim 15 wherein saidfirst filter element comprises high density polyethylene porous filtermedia having an average pore size of approximately 45 μm toapproximately 90 μm.
 19. The upright vacuum cleaner as set forth inclaim 15 further comprising a lid for selectively covering said dirtcup.
 20. The upright vacuum cleaner as set forth in claim 15 furthercomprising a second filter chamber disposed between said outlet of saidhousing section and said inlet of said suction source and a secondfilter element housed in said second filter chamber, for filteringcontaminants from said airstream exhausted from said housing section.